You are somewhat going in the right direction. You have loaded the $order for...

You are somewhat going in the right direction. You have loaded the $order for current user. You need to iterate through the commerce line items, and gather them by their product ids, in a separate array. Then just return the count() of the array. That should do it. The current code will just return the total number of products again.

I am closing this issue as this requirement is project specific.